<!DOCTYPE html>
<html>
<head lang="zh-cmn-Hans">
    <meta charset="UTF-8">
    <title></title>
</head>

<style type='text/css'>
    /*全局*/
    p {
        color: green;
    }

    /*某元素中*/
    div.test p {
        color: red
    }
</style>
<body>
<div class="test">
    <p>
        1234abcd
    </p>
</div>
<p>
    找我呢
</p>
</body>
</html>